Edge-grinding machine



Aug. 25,1942. N. H. KLAGES 2,293,823

EDGE-GRINDING MACHINE Filed July 8, 1941 2 sheets-sheet 1 I l, "I

INVF TOR WWW 75/ MV/S/EMM/ $4 ATTORNEYS Aug. 25, 1942. N.H.KLAGES 2 293,828

EDGE-GRINDING MACHINE Fil ed July 8, 1941 2 Sheets-Sheet 2 INVENTOR Patented Aug. 25, 1942 EDGE-GRINDING MACHINE 7 Norman H. Klages, Greentree, Pa., assignor to a G. W. Klages & Son, a corporation of Pennsyl- Vania Application July 8, 1941, Serial No. 401,408

11 Claims. (01. 51-51) My invention relates to the grinding and dressing of the peripheral edges of plates, typically plates or panes of shatterproof glass that are used in the windows of automobiles. The invention consists in improvements both in apparatus andin method,

The art is familiar with edge-grinding machines of the sort with which my invention has to do. The machines include a chuck that supports a plate of glass and rotates it on, an axis normal to the plane of the plate, while amotordriven grinding wheel bearsyieldingly upon the peripheral edge of the plate. The axisof the yieldingly supported grinding wheel is parallel to the axis of plate rotation; the wheel includes a peripheral groove of semi-circular cross section, and the edge of the plate iseng'aged such groove. The .plate rotates slowly,- the wheel rapidly, and in a single passage oi the periphery of the plate through the point of engagement with the wheel the desired edge finish is provided on the plate.

The plates of shatterproofglass that are now widely used in the windows of motor cars are'of non-circular outline; they are of approximately rectangular form; two of the cornersjof the rectangle are round, and the other two corners are square. The periphery of the plate is straight along one of the longitudinal sides of the rectangle, and such elongate straight portion of the periphery terminates at its opposite ends in the two square corners ofthe plate, while the rest of the periphery of the plate consists in a succession of straight and curved edge portions. It 'so happens that the specifications of the automobile manufacturer do not require the dressing or fine ishing of the elongate straight edge portion that extends between the two square corners of the plate, and thus it is possible, and has been the practice, to mount two plates in the rotary chuck of the grinding machine, with the elongate straight edge portions of the two plates arranged in abutment, or in close parallel relation, and the two plates in common plane. The plate assembly is of approximately circular outline, and all edge portions of the two plates that require dressing are, in the course of chuck rotation, presented to the action of the grinding wheel. In Letters Patent of the United States, No. 2,080,280, granted on my application May 11, 1937, I have illustrated and described such an edge-grinding machine.

In many cases it has been the practice to provide two parallel grooves in the rim of the grinding wheel, and to mount in the chuck two pared on theopposite ends of a single chuck-rotating shaft, and a double-grooved grinding wheel is provided for each chuck, whereby eight plates may be edge-dressed in a single rotation of the shaft.

In the operation of such edge-grinding apparatus, the problem has been to attain uniformity of the eiTect of the grinding wheels upon the edges of the plates. The action of the grinding wheels on the variousedge portions to be dressed is not uniformthe wheels attack the work more slowly on the straightedge portions than on the curved edge portions. Another problemhas been to prevent vibration of the plates and grinding wheels.

In the solution of these problems in accordance with the teachings of my earlier patent, above noted, each grinding wheel is mounted upon' a counter-poised arm that is arranged toswing in the plane of the assembled plates whose edges are to be dressed. The wheel is borne at a relatively long interval from, and to one side of, the fulcrum of the arm, while a counterweight is borne by the arm at a relatively short interval from, and on opposite side of, the fulcrum. The counterweight exceeds the efiective weight of the grinding wheel by the amount required yieldingly to hold the wheel to the edge of the plate with the proper grinding pressure. An electric motor for driving the grinding wheel is mounted on the arm in position where its weight contributes to the efiect of the counterweights, and a conventional belt-and-pulley drive connects the motor to the wheel. When the machine is provided with two plate-supporting chucks, each grinding wheel is thus mounted on a counterweighted arm. I

The chuck-supporting shaft of the machine is driven by an independent motor, and, through the instrumentality of means described in said earlier patent, the speed of rotation of theshaft (and of the chucks borne thereby) is varied automatically in accordance with the variations in the rate of attack of the grinding wheels on the successive edge portions of the plates undergoing treatment. As a straight edge portion of'a rotating plate advances into contact with the grinding wheel, the speed of the plate-supporting chuck is reduced and held at reduced value'until such edge portion has passed from contact with the Wheel. As a succeeding curved edge portion of the rotating plate moves into contact with the wheel, the speed of rotation of the plate-bearing chuck is accelerated; and held at accelerated value so long as such curved edge portion remains in contact with the wheel. And so the angular speed of the slowly rotating plate is regulated,

to render uniform the effect of the grinding wheel on the successive edge portions that are engaged by the wheel.

A brake is organized with each plate-supporting chuck, and in the edge-dressing operation of the machine, the brake exerts a constant drag upon the rotating chuck, with the consequence and effect that chattering and vibration of the plates and rotating machine parts is substantially eliminated.

My present invention proceeds from the discovery that in the solution of the above-mentioned problems yet better results may be gained by shifting the grinding wheel in a direction normal to the axis of plate rotation, in such manner that the point of contact of the wheel with the engaged edge portion of the plate shall always remain in a certain position of orientation with respect to the center of the wheel. In this case it' is desirable that such point of contact shall remain above, and in substantially vertical alignment with, the center of the rotating wheel. In applying this discovery, I provide the fulcrum of the wheel-bearing arms of the machine in a carriage that is adapted to move back and forth in a line perpendicular to the axis of rotation of the peripherally engaged plates. And I provide means for reciprocating the carriage in coordination with the changing angular position and vary ing angular velocit of the rotating plate assembly. In such manner the desired relation between center of wheel rotation and the point of contact of the Wheel with the work is maintained.

In the accompanying drawings I illustrate a machine in which and in the operation of which the invention is realized:

Fig. I is a view of the machine in side elevation;

Fig. II is a view in plan from above of the carriage and arms that support the grinding wheels;

Fig. III is a diagrammatic view, showing partly in vertical section and partly in side elevation the mechanism that effects the reciprocation of the carriage when the machine is in operation. In this view a pair of plates, whose edges are to be dressed, is indicated in broken lines;

Figs. IV, V, VI and VII are diagrammatic views that illustrate successive stages in the edgedressing operation.

Referring to the drawings the machine, which provides an exemplary embodiment of the invention, includes a base 2 that supports a vertically extending housing 3. On each of the opposite sides of the housing (but one side appears in the drawing) a rotary chuck 4 is arranged to support two pairs of glass plates 5; on each side of the housing a, grinding wheel 6 is mounted on an arm I fulcrumed on a shaft 8; the arm carries, in the organization above described, a motor 9 and counterweights l8; and the motor is, by a belt ll (Figs. II and III), connected to a pulley l2 on the axle of the grinding wheel. Gravity, acting upon the counterweights and motor, urges the wheel-bearing end of the arm upward, and maintains the wheel in yielding engagement with the edges of plates 5.

In Fig. III the chuck-supporting shaft I3 of the machine is shown in cross section, and it may be understood that this shaft is journaled in the walls of the housing 3, and that the ends of the shaft extend from the opposite sides of the housing and carry the two chucks 4. The structure of the chucks 4 (Fig. I) is now known to the art, as also is the manner in which a braking drag is imposed upon each chuck.

Within the housing 3 a worm-gear I4 is secured to the chuck-shaft l3, and a worm-pinion l5 meshes with the gear. The pinion is rotated with an angular velocity that is alternately increased and decreased, to the end that the linear advance of the edges of the plates 5 through the points of contact with the grinding wheels shall be alternately accelerated and diminished, after the manner and for the purpose already described. Instrumentalities for effecting such rotation of the chuck-driving gears are described in my earlier patent, and repetition herein is not required for an understanding of the present invention.

The shaft 8, On which the arms 1 are fulcrumed, is secured in a carriage l6 adapted to travel on wheels I! that ride a pair of rails I8. The rails are mounted on a portion of the machine base 2 that extends horizontally to rear of the housing 3, and it will be understood that these rails, as viewed in plan from above the machine, run perpendicularly to the shaft 13 on which the chucks 4 are mounted.

A flexible tension member I9 (say of wire rope Or link chain) is anchored to the carriage at 20, and extending forwardly from such point of anchorage (to the left in Fig. III) the tension member 19 is trained over pulleys 2| and 22 that are suitably mounted in the framework of the machine. The tension member carries a weight 23 at its otherwise free end, and under the effect of this weight the carriage tends constantly to move forwardly (right to left) on the rails. Opposing the effect of the tension member IS on the carriage is a tension member 24; this tension member 24 is anchored to the carriage in common with member l9, but it extends from the carriage in opposite direction, and is trained over a pulley 25 journaled in the base of .the 'machine; from pulley 25 the member 24 passes over pulleys 26 and 21 and is anchored. as at 28, to the stationary housing of the machine. The pulley 26 is mounted in the base of the machine, while the pulley 21 is carried by the distal end of an arm 29 that is pivoted to the housing 3 on a pin 30. The arm 29 carries intermediately a wheel 3| that bears upon the edge of a cam-disc 32 keyed to the shaft I3. The tension imposed by weight 23 on flexible member I9 is manifestly eifective upon flexible member 24, and such tension, in tending as it does to shorten the bight 24a in member 24, exerts a downward pull on the pulley-bearing end of arm 29, holding the wheel 3| to the edge of the cam 32. The cam 32, slowly rotating in unison with the shaft [3, effects the angular oscillation of the arm 29 on its pivot 30, alternately raising and lowering the pulley 21, and alternately increasing and decreasing the length of the bight 24a in flexible tension member 24. In consequence, the carriage I6 is caused slowly to move on the rails l8, backwards and forwards, slowly reciprocating the arms I in horizontal direction, and correspondingly shifting the rapidly rotating grinding wheels in engagement with the edges of plates 5. As already mentioned, the angular velocity of the chuck-rotating shaft [3 is automatically varied, and it will be perceived that, with the cam 32 keyed to such shaft, the movement of the reciprocating carriage, together with the arms I and grinding wheels 6 borne thereby, is accelerated and diminished in coordination with the changes in the rotational velocity of the chuck-borne plates 5. The cam 32 is so particularly patterned as to provide the most effective reciprocative movement of the rotating grinding wheels in engagement with the edges of the rotating plates 5.

In Figs. III to VII successive stages of the edgegrinding operation are indicated. The curved edge or corner portion a of one of a pair of rotating plates 5, 5 is in Fig. III shown in contact with the rotating grinding wheel 6. It will be understood that in this stage of the edge-dressing operation the rotational velocity of the plate-supporting chuck is maintained at accelerated value, while the carriage it moves in right-to-left direction, as indicated by the arrow a. The rightto-left movement of the carriage, it will be perceived, is efiective to maintain the point of contact between the edge of the rotating plate and the grinding wheel in substantially vertical alignment with the wheels axis. As the curved edge portion 5a passes from engagement with the wheel and the straight edge portion 51) enters engagement, the rotational velocity of the chuck is diminished, and the movement of the carriage is reversed. The arrow b in Figs. IV and V indicates the left-to-right direction in which the carriage shifts the grinding wheel while the edge portions 51) of the two rotating plates move through the point of engagement with the wheel. As the curved corner 50 of the second plate reaches the point of grinding engagement with the wheel, the movement of the carriage is again reversed, and the angular velocity of the plate-supporting chuck is again accelerated. While the edge portion 50 is subjected to the grinding action, the horizontal movement of the grinding wheel is in right-to-left direction; that is to say, the wheel moves with the point of attack upon the work and maintains the desired orientation of such point of attack with the axis of the grinding wheel. When the edge portion 50 passes from contact with the wheel, the rotational velocity of the plates is again reduced, and the horizontal movement of the carriage is again reversed (cf. VII). And so the rotating wheel is moved back and forth in coordination with the changing position and varying velocity of the rotating plate assembly. As a curved corner of a plate passes from engagement with the wheel, the wheel, in grinding engagement with the succeeding straight edge portion, moves backward (left to right, as here illustrated), meets the next-succeeding curved corner of the assembled plates, and then advances with it. Thus, the point of engagement between the grinding wheel and the work is maintained in substantial vertical alignment with the axis of the wheel.

By virtue of the improvements described, advantages of the nature indicated are obtained. Additionally, it becomes possible to increase the pressure of the wheel upon the edges of the glass plates by as much as fifty percent, and this results in from thirty to forty percent. increase in the speed of the edge-dressing operation.

Needless to say, various modifications and elaborations of the apparatus and method described are permissible within the ambit of the invention defined in the appended claims.

I claim as my invention:

1. In apparatus for finishing the edges of plates, including a plate support that is rotatable on an axis normal to the plate body, and a rotating grinding wheel that is yieldingly supported and that yieldingly engages the edge of' the rotating plate; the invention herein described in which the grinding wheel support includes a carriage mounted for movement in a line extending transversely of the axis of plate rotation, and means for reciprocating the wheel-supporting carriage on said line of movement while the wheel-engaged plate is in rotation.

2. In apparatus for finishing the edges of plates, including a plate support that is rotatable on an axis normal to the plate body, and a rotating grinding wheel that is yieldingly supported and that yieldingly engages the edge of the rotating plate; the invention herein described in which the grinding wheel support includes a carriage mounted for movement in a line extending transversely of the axis of plate rotation, and means for reciprocating such wheel-supporting carriage on said line of movement in definite coordination with the rotation of said plate.

3. In apparatus for finishing the edges of plates, including a plate support that is rotatable on an axis normal to the plate body, and a rotating grinding wheel that is yieldingly supported and that yieldingly engages the edge of the rotating plate; the invention herein described inwhich the grinding wheel support includes a carriage mounted for movement in a line that parallels the plane defined by the peripheral edge of the plate body, and means for reciprocating the wheel-supporting carriage on said line while the wheel-engaged plate is in rotation.

4. In apparatus for finishing the edges of plates, including a plate support rotatable on an axis normal to the :plate body, a rotating grinding wheel, an arm pivoted to a support, said arm \carrying said rotating grinding wheel at an interval from the pivot axis and sustaining the rim of the rotating wheel in yielding engagement with the edge of said plate; the invention herein described in which said support to which said arm is pivoted comprises a carriage that is movable, while the wheel-engaged plate is in rotation, in a direction extending transversely of the axis of .plate rotation, and means for moving the .carriage in synchronism with the rotating plate.

5. Apparatus for finishing the edges of plates comprising a rotating support for a plate, means including a rotating grinding wheel yieldingly engaging the edge of the rotating plate, and means for effecting the travel of the rotating wheel longitudinally of the edge of the plate advancing into contact with the wheel, said means adapted to shift said grinding wheel relatively to, and in a direction extending transversely of, the axis of the rotary support and in predetermined coordination with the rotation of the plate.

6. Apparatus for finishing the edges of plates comprising a rotating support for a plate, means including a rotating grinding wheel yieldingly engaging the edge of the rotating plate, and means for effecting the travel of the rotating wheel longitudinally of the edge of the plate advancing into contact with the wheel.

7. The method herein described which comprises sustaining a rapidly rotating dressing wheel in yielding contact with the edge of .a non-circular plate, slowly rotating the plate to efiect the advance of the edge of the plate through the point of contact thereof with the dressing wheel, and in the course of such operation shifting the rotating wheel relatively to, and in a direction extending transversely of, the axis on which the plate is rotated, and thereby maintaining said point of contact of the wheel with the edge of the plate in predetermined orientation with respect to the center of rotation of the wheel.

8. The method herein described which comprises sustaining a rapidly rotating dressing wheel in yielding contact with the edge of a noncircular plate, slowly rotating the plate to effect the advance of the edge of the plate through the point of contact thereof with the dressing wheel, and in the course of such operation varying the speed of rotation of the plate relatively to the speed of rotation of said wheel, and shifting the rotating wheel relatively to, and in a direction extending transversely of, the axis on which the plate is rotated, and thereby maintaining said point of contact of the wheel with the edge of the plate in predetermined orientation with respect to the center of rotation of the wheel.

9. The method herein described which comprises sustaining a rapidly rotating dressing wheel in yielding contact with the edge of a noncircular plate, slowly rotating the plate to effect the advance of the edge of the plate through the point of contact thereof with the dressing wheel, and in the course of such operation shifting the rotating wheel with varying velocity relatively to, and in a direction extending transversely of, the axis on which the plate is rotated, and thereby maintaining said point of contact of the wheel with the edge of the plate in predetermined orientation with respect to the center of rotation of the wheel.

10. The method herein described which comprises sustaining a rapidly rotating dressing wheel in yielding contact with the edge of a noncincular plate, slowly rotating the plate to effect the advance of the edge of the platethrough the point of contact thereof with the dressing wheel, and in the course of such operation varying the speed of rotation of the plate relatively to the speed of rotation of said wheel, and shifting the rotating wheel with varying velocity relatively to, and in a direction extending transversely of, the axis on which the .plate is rotated, and thereby maintaining said point of contact of the wheel with the edge of the plate in predetermined orientation with respect to the center of rotation of the wheel.

11. The method herein described which com- ,prises sustaining a rapidly rotating dressing wheel in yielding contact with the edge of a noncircular plate, slowly rotating the .plate to efiect the advance of the edge of the plate through the point of contact thereof with the dressing wheel, and in the course of such operation shifting the rotating wheel relatively to and transversely of the axis or plate rotation and efiecting the travel of the rotating wheel longitudinally of the advancing edge of the plate.

NORMAN H. KLAGES. 

